In Patent Literature 1, there is disclosed an air-conditioning apparatus. The air-conditioning apparatus includes a gas sensor provided on an outer surface of an indoor unit and configured to detect refrigerant, and a controller configured to control an indoor air-sending fan to rotate when the gas sensor detects the refrigerant. The air-conditioning apparatus can detect leaked refrigerant by the gas sensor when the refrigerant leaks to an indoor space through an extension pipe connected to the indoor unit or when refrigerant leaked inside the indoor unit passes through a gap of a casing of the indoor unit to flow outside of the indoor unit. Further, the indoor air-sending fan is rotated when the leakage of the refrigerant is detected so that indoor air is sucked through an air inlet formed in the casing of the indoor unit and air is blown off to the indoor space through an air outlet. In this manner, the leaked refrigerant can be diffused.